Method for embedding a component in a base and forming a contact

ABSTRACT

The invention includes a method, in which at least some of the semiconductor components forming part of an electronic circuit are embedded in a base, such as a circuit board, during the manufacture of the base. Thus, the base structure is basically manufactured around the semiconductor component. According to the invention, at least one conductive pattern and through holes for the semiconductor components are made in the base. Thereafter, the semiconductor components are placed in the holes in alignment with the conductive pattern. The semiconductor components are attached to the structure of the base, and one or more conductive pattern layers are made in the base in such a way that at least one conductive pattern forms an electrical contact with the contact areas of the surface of the semiconductor component.

The present invention relates to a method for embedding one or morecomponents in a base and for forming contacts in them.

The bases that are processed using the methods to which the presentinvention relates are used as bases for electrical components, typicallysemiconductor components and particularly microcircuits, in electronicproducts. The task of the base is to provide a mechanical attachmentbase for the components and the necessary electrical connections to theother components on the base and outside the base. The base can be acircuit board, so that the method that is the object of the invention isclosely related to circuit-board manufacturing technology. The base canalso be some other base, for example, a base used for packaging acomponent or components, or the base of an entire functional module.

Circuit-board manufacturing technologies differ from microcircuitmanufacture in, among other things, the fact that the substrate used inmicrocircuit manufacturing technologies is a semiconductor material,whereas the base material of a circuit board is an insulator.Microcircuit manufacturing technologies are also typically considerablymore expensive than circuit-board manufacturing technologies.

Circuit-board manufacturing technologies differ from packagingtechniques in that packaging techniques are intended to form a packagearound a semiconductor component, which will facilitate its handling.The surface of a package of a semiconductor component has contact parts,typically protrusions, which allow the packaged component to be easilyinstalled on a circuit board. A semiconductor package also containsconductors, through which voltage can be connected to the actualsemiconductor, connecting the protruding contact parts outside thepackage to the contact areas on the surface of the semiconductorcomponent.

However, the packages of components manufactured using conventionaltechnologies take up a considerable amount of space. The miniaturizationof electronic devices has led to an attempt to eliminate the packagingof semiconductor components. For this purpose, the so-called flip-chiptechnology for instance, has been developed, in which a semiconductorcomponent without a package is assembled directly onto the surface ofthe circuit board. There are, however, many difficulties in flip-chiptechnology. For example, problems can arise with the reliability ofconnections, especially in applications in which mechanical stressesarise between the circuit board and the semiconductor component.Mechanical stresses must be evened by adding a suitable underfillbetween the chip and the circuit board. This procedure slows down theprocess and increases manufacturing costs. Stresses arise particularlyin applications in which a flexible circuit board is used and thecircuit board is flexed strongly.

An object of the invention is to create a method, by means of whichunpacked microcircuits can be attached to a base and provided withcontacts reliably but economically.

The invention is based on embedding the semiconductor components, or atleast some of them, in a base, such as a circuit board, during themanufacture of the base, whereby part of the base structure ismanufactured around the semiconductor components. According to theinvention, at least one conductive pattern is first manufactured in thebase, as are through holes for the semiconductor components. After this,the semiconductor components are placed in the holes, in alignment withthe conductive pattern. The semiconductor components are attached to thestructure of the base and one or more layers of conductive patterns aremanufactured in the base, in such a way that at least one conductivepattern forms an electrical contacts with the contact areas on thesurface of the semiconductor component.

Considerable advantages are gained with the aid of the invention. Thisis because, with the aid of the invention, a circuit board can bemanufactured with the semiconductor components embedded inside it. Theinvention also makes it possible to manufacture a small and reliablecomponent package around a component.

The invention also permits a large number of embodiments, which providesignificant additional advantages.

For example, by means of the invention, the component's packaging stage,the circuit board's manufacturing stage, and the assembly andcontact-making stage of the semiconductor components can be combined toform a single totality. The combination of the various process stagesbrings important logistic benefits and permits the manufacture of asmaller and more reliable electronic module. There is the furtheradvantage that such a manufacturing method can largely exploit circuitboard manufacturing and assembly technologies that are in general use.

The composite process according to a preferred embodiment of theinvention is, in its totality, simpler than, for example, manufacturinga circuit board and using flip-chip technology to attach the componentsto the circuit board. By means of such preferred embodiments, thefollowing advantages over the conventional solution are obtained:

-   -   Soldering is not required to form contacts with the components.        Instead, an electrical contact can be manufactured by growing        conductors on top of the contact areas of a semiconductor        component. This means that there is no need to use molten metal        to connect the components, so that compounds are not formed        between metals. Compounds between metals are generally brittle;        thus, reliability is improved compared to connections made by        soldering. Particularly in small connections, the brittleness of        the metal compounds in the connections causes great problems.        According to an exemplary embodiment, it is possible to achieve        clearly smaller structures in a solderless solution than in        soldered solutions. The solderless contact-making method also        has the advantage that high temperatures are not required to        form contacts. A lower process temperature permits greater        choice when selecting other materials of the circuit board, the        component package, or the electronics module. In the method, the        temperature of the circuit board, the component, and the        conductive layer directly connected to the component can be kept        in the range 20–85° C. Higher temperatures, for example, of        about 150° C., may be needed only when hardening (polymerizing)        any polymer films used. However, the temperature of the        baseboard and the components can be kept under 200° C. during        the entire process. In the method, it is also possible to use        polymer films, which are hardened in other ways than due to the        effect of a high temperature, for example, chemically, or by        electromagnetic radiation, such as ultraviolet light. In such an        exemplary embodiment of the invention, the temperature of the        baseboard and the components can be kept under 100° C. during        the entire process.    -   Because the use of the method permits the manufacture of smaller        structures, the components can be spaced more closely. The        conductors between the components can then also be shorter while        the electrical properties of the electronic circuit improve, for        example, by reducing losses, interference, and delay times.    -   The method also permits the manufacture of three-dimensional        structures, as the bases and the components embedded in the        bases can be assembled on top of each other.    -   In the method, it is also possible to reduce the interfaces        between different metals.    -   The method permits a lead-free process.

The invention also permits other preferred embodiments. In connectionwith the invention, flexible circuit boards, for instance, can be used.Further, the process permits circuit boards to be assembled on top ofeach other.

With the aid of the invention, it is also possible to manufactureextremely thin structures, in which the semiconductor components are,despite its thinness, entirely protected within a base, such as acircuit board.

Because the semiconductor components can be placed entirely inside thecircuit board, the joints between the circuit board and thesemiconductor components are mechanically durable and reliable.

In the following, the invention is examined with the aid of examples andwith reference to the accompanying drawings.

FIG. 1 shows a series of cross-sections of one process according to anexemplary embodiment of the invention.

FIG. 2 shows a series of cross-sections of a second process according toan exemplary embodiment of the invention.

FIG. 3 shows a series of cross-sections of a third process according toan exemplary embodiment of the invention.

The series of illustrations shown in FIG. 1 show one possible processaccording to the invention. In the following, the process of FIG. 1 isexamined in stages:

Stage A (FIG. 1A):

In stage A, a suitable baseboard 1 is selected for the circuit-boardmanufacturing process. The baseboard 1 can be, for example, aglass-fibre reinforced epoxy board, such as an FR4-type board. In theexample process, the baseboard 1 can thus be an organic board, as theexample process does not require high temperatures. A flexible and cheaporganic board can thus be selected for the baseboard 1. Typically aboard that is already coated with a conductive material 2, usuallycopper, is selected for the baseboard 1. Of course, an inorganic boardcan also be used.

Stage B (FIG. 1B):

In stage B, through holes 3 are made in the baseboard for electricalcontacts. The holes 3 can be made, for example, with some known methodused in circuit-board manufacture, such as mechanical drilling.

Stage C (FIG. 1C):

In stage C, metal 4 is grown into the through holes made in stage B. Inthe example process, the metal 4 is also grown on top of the circuitboard, thus also increasing the thickness of the conductive layer 2.

The conductive material 4 to be grown is copper, or some other materialwith sufficient electrical conductivity. Copper metallizing can takeplace by coating the holes with a thin layer of chemical copper and thencontinuing the coating using an electrochemical copper-growing method.Chemical copper is used in an exemplary embodiment, as it will surfaceon top of a polymer and act as an electrical conductor inelectrochemical coating. The metal can thus be grown using awet-chemical method, so that the growth is cheap. Alternatively, theconductive layer 4 can be made, for example, by filling the throughholes with an electrically conductive paste.

Stage D (FIG. 1D):

In stage D, the conductive layer on the surface of the circuit board ispatterned. This can be done by utilizing generally known circuit-boardmanufacturing methods. The patterning of the conductive layer isaligned, for example, on the holes made in stage B.

The manufacture of the conductor pattern can take place, for example, bylaminating, on the surface of the metal 4, a photolithographic polymerfilm on which the desired conductive pattern is formed by directinglight through a patterned mask. After exposure, the polymer film isdeveloped when the desired areas are removed from it and the copper 4under the polymer is revealed. Next, the copper revealed under the filmis etched away, leaving the desired conductive pattern. The polymer actsas a so-called etching mask, and openings 5, at the foot of which thebaseboard of the circuit board is revealed, are formed in the metallayer 4. After this, the polymer film is also removed from on top of thecopper 4.

Stage E (FIG. 1E):

In stage E, holes 6 are made in the baseboard for the microcircuits. Theholes extend through the entire baseboard, from the first surface 1 a tothe second surface 1 b. The holes may be made, for example, bymechanically milling by means of a milling machine. The holes 6 can alsobe made, for example, by stamping. The holes 6 are aligned relative tothe conductive patterns 4 of the circuit board. The holes 3 made duringstage B can also be used to aid alignment, but then too the alignment isrelative to the conductive patterns 4, as the conductive patterns 4 havea specific position in relation to the holes 3.

Stage F (FIG. 1F):

In stage F, tape 7 or something similar is laminated over the holes 6.The tape 7 is laminated by stretching it straight over the hole 6 alongthe second surface 1 b of the baseboard. The tape is intended to holdthe components to be assembled in the next stage in place, until thecomponents have been secured to the baseboard using the final attachmentmethod.

Stage G (FIG. 1G):

In stage G, the microcircuits 8 are assembled in the holes 6, from theside of the first surface 1 a of the baseboard. Assembly can take placeusing a precision assembly machine, the microcircuits 8 being alignedrelative to the conductive patterns of the circuit board. As in stage E,the holes made in stage B can be used to aid alignment.

The microcircuits 8 are assembled in such a way that they adhere to theadhesive surface of the tape 7 in the ‘bottoms’ of the holes 6.

Stage H (FIG. 1H):

In stage H, the microcircuits 8 are attached to the baseboard of thecircuit board by using a filler substance 9 to fill the holes made forthe microcircuits. In an exemplary embodiment, this stage is carried outby spreading casting epoxy into the holes and on top of themicrocircuits 8, from the side of the first surface (1 a) of the circuitboard. The epoxy is smoothed with a spatula and is hardened by curing inan autoclave.

Stage I (FIG. 1I):

In stage I, the tape laminated in stage F is removed.

Stage J (FIG. 1J):

In stage J, a polymer film 10 is formed on the surface of the circuitboard, followed by a thin metal coating 11 on top of the polymer film.The film is preferably formed on both surfaces of the circuit board, butat least on the second surface (1 b) of the circuit board.

In an exemplary embodiment, stage J is carried out by laminating a thinpolymer film (e.g., c. 40 μm) on the surface of the circuit board, ontop of which is a layer of copper (e.g., c. 5 μm). Lamination takesplace with the aid of pressure and heat. In the example process, thefilm is thus an RCC (Resin Coated Copper) foil.

The polymer film can also be made by, for example, spreading polymer ina liquid form on the circuit board. Thus lamination is not essential instage J. What is essential is that an insulating layer, typically apolymer film, is made on the circuit board, which contains the embeddedcomponents, particularly embedded microcircuits. The polymer film itselfcan be, according to the embodiment, a filled or unfilled polymer film.The polymer film can also be coated with metal, but this is notessential, as the conductive surface can also be made later, on top of apolymer layer that is already attached to the circuit board.

Stage J makes it possible to use conventional manufacturing methods andwork stages used in circuit board manufacture in the example process andnevertheless to be able to embed microcircuits and other componentsinside the circuit board.

Stage K (FIG. 1K)

In stage K, holes 12 are made in the polymer film 10 (and at the sametime in the conductive foil 11), through which it is possible to createcontacts with the conductive patterns and feed-throughs (conductivematerial 4) of the circuit board and with the microcircuits 8.

The holes 12 can be made, for example, using a laser, or some othersuitable method. The conductive patterns made in stage D, or the throughholes made in stage B can be used for alignment.

Stage L (FIG. 1L):

Stage L corresponds to stage C. In stage L, a conductive layer 13 ismade in the holes 12 and on the surfaces of the circuit board.

In the example process, the feed-throughs (holes 12) are first of allcleaned using a three-stage desmear treatment. After this, thefeed-throughs are metallized by first forming a catalysing SnPd surfaceon the polymer and after that depositing a thin layer (about 2 μm) ofchemical copper onto the surface. The thickness of the copper 13 isincreased by electrochemical deposition.

Alternatively, the feed-throughs can be filled with an electricallyconductive paste or made using some other suitable micro-via metallizingmethod.

Stage M (FIG. 1M):

In stage M, a conductive pattern is formed in the same way as in stageD.

Stages N and O (FIGS. 1N and 1O):

In stages N and O, a photolitographic polymer 14 is spread on thesurfaces of the circuit board and the desired pattern is formed in thepolymer 14 (in a manner similar to that in stages D and M). The exposedpolymer film is developed, but the polymer film pattern remaining on thecircuit board is not removed.

Stage P (FIG. 1P):

In stage P, the connection areas of the polymer film pattern formed inthe previous stage are coated 15. The coating 15 can be made with, forexample, a Ni/Au coating, or an OSP (organic surface protection).

The exemplary embodiment of FIG. 1 depicts one process, which can beused to exploit our invention. Our invention is thus in no wayrestricted to the process described above, but instead the inventioncovers a large group of different processes and their end products, tothe full extent of the Claims and allowing for equivalencyinterpretations. In particular, the invention is in no way restricted tothe layout shown in the exemplary embodiment of FIG. 1; instead, it willbe obvious to one versed in the art that the processes according to ourinvention can be used to manufacture many kinds of circuit boards, whichdiffer greatly from the examples disclosed here. Thus, the microcircuitsand connections of the figures are only shown to illustrate themanufacturing process. Many changes can thus be made to the process ofthe example disclosed above, without deviating from the idea accordingto the invention. The changes can relate to the manufacturing techniquesdepicted in the various stages, or, for example, to the mutual sequenceof the stages. For example, stage B can equally well be carried outafter stage D, i.e. the procedure can include aligning the drill on thepattern, instead of aligning the pattern on the drilled holes.

Other necessary stages can also be added to the process of the exampledisclosed above. For example, a foil that protects the surface of thecircuit board during the casting taking place in stage H can belaminated onto the first side (1 a) of the circuit board. Such aprotective foil is manufactured so that it covers all the other areasexcept for the holes 6. The protective foil keeps the surface of thecircuit board clean when the casting epoxy is spread with the spatula.The protective foil can be made in a suitable stage before stage H andis removed from the surface of the circuit board immediately after thecasting.

With the aid of the method, it is also possible to manufacture componentpackets to be attached to the circuit board. Such packets can alsoinclude several semiconductor components, which are connectedelectrically to each other.

The method can also be used to manufacture entire electrical modules.The process shown in FIG. 1 can also be applied in such a way that theconductive structure is made only on the second side (1 b) of thecircuit board, to which the contact surfaces of the microcircuit areoriented.

The method makes it possible to manufacture, for example, circuit boardsor electrical modules, in which the thickness of the baseboard used isin the range 50–200 microns and the thickness of the microcircuit andmicrocircuits is in the range 50–150 microns. The pitch of theconductors can vary, for example, in the range 50–250 microns while thediameter of the micro-feed-throughs can be, for example, 15–50 microns.Thus, the total thickness of a single board in a one-layer constructionwill be about 100–300 microns.

The invention can also be applied in such a way that circuit boards areassembled on top of each other, thus forming a multi-layer circuitstructure, in which there are several circuit boards manufacturedaccording to the exemplary embodiment of FIG. 1 set on top of each otherand connected electrically to each other. The circuit boards set on topof each other can also be circuit boards in which the conductivestructure is formed only on the second side 1 b of the circuit board,but which nevertheless include feed throughs, through which anelectrical contact can also be formed to the microcircuits from thefirst side of the circuit board. FIG. 2 shows one such process.

FIG. 2 shows the connection of circuit boards to each other. In thefollowing, the process is described in stages.

Stage 2A (FIG. 2A):

Stage 2A depicts the circuit boards being set on top of each other. Thelowest circuit board can be obtained, for example, after stage I of amodified process of FIG. 1. In this case, the process of FIG. 1 is thenmodified by omitting stage 1C.

The middle and upper circuit boards in turn can be obtained after stageM of a modified process of FIG. 1, for instance. In this case, theprocess of FIG. 1 is modified by omitting stage 1C and performing stagesJ, K, and L on only the second side (1 b) of the circuit board.

In addition to the circuit boards, FIG. 2A also shows pre-preg epoxylayers 21 placed between the circuit boards.

Stage 2B (FIG. 2B):

In stage 2B, the circuit boards are laminated together with the aid ofpre-preg epoxy layers 21. In addition, a metal-coated polymer film 22 ismade on both sides of the circuit board. The process corresponds tostage J of the process of FIG. 1.

Stage 2C (FIG. 2C):

In stage 2C, holes 23, for the formation of contacts, are drilled in thecircuit board.

After Stage 2C, the process can be continued for example as follows:

Stage 2D:

In stage 2D, conductive material is grown on top of the circuit boardand in the through holes 23, in the same way as in stage 1C.

Stage 2E:

In stage 2E, the conductive layer on the surface of the circuit board ispatterned in the same way as in stage 1D.

Stage 2F:

In stage 2F, a photolitographic polymer is spread on the surfaces of thecircuit board and the desired pattern is formed in the polymer in thesame way as in stages 1N and 1O. The exposed polymer film is developed,but the polymer film pattern remaining on the circuit board is notremoved.

Stage 2G:

In stage 2G, the connection areas of the polymer film pattern formed inthe previous stage are metallized in the same way as in stage 1P.

On the basis of the example of FIG. 2, it is obvious that the method canalso be used to manufacture many kinds of three-dimensional circuitstructures. For example, the method can be used in such a way thatseveral memory circuits are placed on top of each other, thus forming apacket containing several memory circuits, in which the memory circuitsare connected to each other to form an operational totality. Such apacket can be termed a three-dimensional multichip module. The chips insuch modules can be selected freely and the contacts between the chipscan be easily made according to the selected circuits.

The invention also permits electromagnetic protection to be made aroundthe component embedded in the base. This is because the method of FIG. 1can be modified in such a way that the holes 6 depicted in stage 1E canbe made in connection with the making of the holes 3 carried out instage 1B. In that case, the conductive layer 4 to be made in stage 1Cwill also cover the side walls of the holes 6 made for the components.FIG. 3A shows a cross-section of the base structure as it is after stage1F in the process modified in the aforesaid manner.

After the intermediate stage shown in FIG. 3A, the process can becontinued by assembling the microcircuits in a similar way to stage 1G,the microcircuits being attached similarly to stage 1H, the tape removedsimilarly to stage 1I, and polymer and metal foils being made on bothsurfaces of the circuit board in a similar way to stage 1J. FIG. 3Bshows an example cross-section of the base structure after these processstages.

After the intermediate stage shown in FIG. 3B, the process can becontinued by making holes, similar to those of stage 1K, in the polymerfilm, for making contacts. After this, a conductive layer is made in theholes and on the surfaces of the board similarly to stage 1L. FIG. 3Cshows an example cross-section of the base structure after these processstages. For reasons of clarity, the conductive layer made similarly tostage 1L in the holes and on the board surfaces is highlighted in black.

After the intermediate stage shown in FIG. 3C, the process can becontinued by patterning a conductive layer on the surfaces of the boardas in stage 1M and by coating the surfaces of the board as in stage 1N.After these stages, the microcircuits are surrounded by a nearlyunbroken metal foil, which forms an effective protection againstinterference caused by electromagnetic interaction. This construction isshown in FIG. 3D. After the intermediate stage shown in FIG. 3D, stagescorresponding to stages 1O and 1P are carried out, in which a protectivefoil and connections are made on the surface of the circuit board.

In FIG. 3D, the cross-sections of the metal layers protecting themicrocircuits are highlighted in black. In addition, the background ofthe microcircuits is highlighted with cross-hatching. The cross-hatchingis intended to be a reminder that all the sides of a hole made for amicrocircuit are covered by a metal foil. Thus the microcircuit issurrounded laterally with an unbroken metal foil. In addition to this, ametal plate can be designed above the microcircuit, which is made inconnection with the making of the circuit board's conductive pattern.Similarly, a metal foil that is as complete as possible is made belowthe microcircuit. The making of contacts below the microcircuit meansthat small gaps must be made in the metal foil, as shown in FIG. 3D, forinstance. These gaps can, however, be made so narrow laterally, or,correspondingly, so thin vertically, that they do not weaken theprotective effect obtained against electromagnetic interference.

When examining the example of FIG. 3D, it must also be take into accountthat the final structure also contains parts extending at right anglesto the plane shown in the figure. Such a structure extending at rightangles is shown by the conductor connected to the contact bump on theleft-hand side of the left-hand microcircuit of FIG. 3D, which runstowards the viewer from between the metal foil surrounding themicrocircuit laterally and the conductive layers below the microcircuit.

The solution shown by FIG. 3D thus provides the microcircuit withexcellent protection against electromagnetic interference. As theprotection is made immediately around the microcircuit, the constructionalso protects against mutual interference arising between the componentscontained in the circuit board. Most of the electromagnetic protectivestructure can also be earthed, as the metal foil surrounding themicrocircuits laterally can be connected electrically to the metal plateabove the circuit. The connections of the circuit board, can, in turn,be designed in such a way that the metal plate is earthed through theconductive structure of the circuit board.

1. A method for embedding a component in a base and for formingelectrical contact with the component, the method comprising talking abaseboard as the base, making a hole in the baseboard, placing acomponent in the hole, the component having, on its first surface,contact areas or contact protrusions for creating electrical contacts,securing the component in place in the hole made in the baseboard,making an insulating layer on at least one of a first and second surfaceof the baseboard, in such a way that the insulating layer covers thecomponent, making contact openings for the component in the insulatinglayer, and making conductors to the contact openings and on top of theinsulating layer, in order to form electrical contacts with thecomponent, characterized by making conductive patterns on the baseboard,selecting the position of the hole and aligning the component inrelation to the conductive patterns made on the baseboard, and aftermaking the hole laminating a tape or a tape-like film on the secondsurface of the baseboard, placing the component in the hole made in thebaseboard from the first-surface side of the baseboard, so that thefirst surface of the component lies against the tape or tape-like filmand is substantially on the same level as the second surface of thebaseboard, securing the component in place in the hole made in thebaseboard by filling the hole with a filler material, and after securingthe component, removing the tape or tape-like film laminated on thesecond surface of the baseboard.
 2. A method according to claim 1, inwhich the hole, which is made in the baseboard corresponding to the baseof the component, is a through hole.
 3. A method according to claim 2,in which conductive material is grown on the side walls of the hole madefor a component, in order to create interference protection around thecomponent.
 4. A method according to any of claims 1–3, in which thecomponent to be placed in the hole is a microcircuit.
 5. A methodaccording to claim 4, in which, after the securing of the microcircuitthe tape or tape-like film laminated on the second surface of thebaseboard is removed, an RCC foil is laminated onto the second surfaceof the baseboard, and conductive patterns and contact openings for thecomponents are made in the RCC foil.
 6. A method according to claim 4,in which holes are made for feed-throughs and, after the securing of themicrocircuit the tape or tape-like film laminated on the second surfaceof the baseboard is removed, RCC foils are laminated onto the first andsecond surfaces of the baseboard, conductive patterns and contactopenings for the component and feed-throughs are made in the RCC foillaminated onto the second surface of the baseboard, and conductivepatterns and contact openings for the feed-throughs are made in the RCCfoil laminated onto the second surface of the baseboard.
 7. A methodaccording to claim 4, in which, after the securing of the microcircuitthe tape or tape-like film laminated on the second surface of thebaseboard is removed, a pre-preg epoxy foil is made on the secondsurface of the baseboard, contact openings for the component are made inthe epoxy foil, and conductive patterns are made on top of the epoxyfoil.
 8. A method according to claim 4, in which holes for feed-throughsare made in the base, and, after the securing of the microcircuit thetape or tape-like film laminated on the second surface of the baseboardis removed, pre-preg epoxy foils are laminated onto the first and secondsides of the baseboard, contact openings for the component andfeed-throughs are made in the epoxy foil of the second surface of thebaseboard, and contact openings for the feed-throughs are made in theepoxy foil of the first surface of the baseboard.
 9. A method accordingto any of claim 4–8, in which an electrical contact is formed with themicrocircuit from the direction of the second surface of the baseboard,after the microcircuit has been placed in the hole made in thebaseboard.
 10. A method according to any of claims 4–9, in which anelectrical contact is formed with the microcircuit by growing conductivematerial in the contact areas of the microcircuit, or on top of itscontact protrusions.
 11. A method according to any of claims 4–10, inwhich the electrical contact with the microcircuit is formed withoutsolder using a circuit-board manufacturing technology.
 12. A methodaccording to any of claims 1–11, in which more than one component isembedded in the base in a corresponding manner.
 13. A method accordingto claim 12, in which a separate hole is made in the baseboard for eachcomponent to be embedded in the base and each component to be embeddedin the base is located in its own hole.
 14. A method according to any ofclaim 1–13, in which at least two microcircuits are embedded in thebase, and in which a conductive layer is grown, which is connecteddirectly to the contact areas or contact protrusions of the at least twomicrocircuits, in order to connect the microcircuits electrically toeach other to form an operational totality.
 15. A method according toany of claims 1–14, in which a multi-layer structure is manufactured, inwhich there are at least four conductive layers on top of each other.16. A method according to any of claims 1–15, in which a first base andat least one second base are manufactured and the bases are assembledand secured on top of each other in such a way that the bases arealigned in relation to each other.
 17. A method according to any ofclaims 1–15, in which a first and a second base and an intermediatelayer are manufactured, the second base is placed above the first baseand the second base is aligned in relation to the first base, theintermediate layer is placed between the first and the second bases, andthe first and second bases are laminated to each other with the aid ofthe intermediate layer.
 18. A method according to claim 17, in which atleast one third base and an intermediate layer for each third base aremanufactured, each third base is placed in turn above the first andsecond bases and each third base is aligned in relation to one of thelower bases, an intermediate layer is placed beneath each third base,and the first, second, and each third base are laminated to each otherwith the aid of the intermediate layers.
 19. A method according to anyof claims 16–18, in which holes for feed-throughs are drilled throughthe bases secured on top of each other and conductors are made in thedrilled holes for connecting the electronic circuits of each base toeach other to form an operational totality.
 20. A method according toany of claims 1–19, in which the temperature of the baseboard,component, and conductive layer connected directly to the component, is,during the process, less than 200° C. and preferably in the range 20–85°C.
 21. An electronic module, which is manufactured using a methodaccording to any of claims 1–20.